Corrosion resistant articles of manufacture



Patented Feb. 7, 1933 UNITED STATESPATENT-OFFICE,

raanmucx u. ancxar, or NEW YORK, N.- assmnoaro anacrao un'rmuaerca'r.

COMPANY, A CORPORATION OF WEST VIRGIN IA CORROSION RESISTANT ARTICLES 01' MANUFACTURE Io Drawing. Original application flied April 29, 1980, Serial No. 448,98. Divided and application filed October 29, 1932. Serial No. 640,840.

To increase the resistance of iron to corrosion and to oxidation at elevated temperatures it is customary to incorporate chromium in various quantities. When the chromium content rises to about eighteen ,per cent or higher with the carbon content suitably low alloys are produced which have a wide field of application due to their excellent resistance to various corrosive influences.

These .alloys, however, tend to be deficient in workability and they do not possess the physical roperties required to adapt them to severe eep drawing operations.

It has been proposed and has become a common practice to incorporate a content of nickel, for example eight to fifteen per cent, with such a corrosion-resistant iron-chromium base in order to enhance the working roperties. This expedient is quite effective or the purpose referred to and the iron-chromium-nickel compositions have gone into extensive use. It has been found, however, that the incorporation of nickel markedly diminishes the ability of the metal to withstand the action of sulphur dioxide, hydrogen sulphide and other sulphur compounds, and in certain applications where sulphur compounds are encountered at elevated temperatures and where a high degree of ductility .should be preserved, neither the binary iron= ability can be impartedto corrosion resist;

ant iron-chromium alloys by appropriate additions of manganese and that unlike nickel the manganese does not appear to impair the resistance to corrosion in any respect. In comparative tests the iron-chromium-manganese alloys are found to resist the action of such agents as sulphurous acid and moist hydrogen sulphide at ordinary and elevated temperatures, substantially to the same degree as the most resistant binary chromium irons, and far better than any iron-chromium-nickel alloys which have come to my attention. I

The best properties are exhibited by alloys containing from about fifteen to about twenty-two per cent of chromium. To develop the maximum de cc of workability prefer a proportion .o manganese within the range embraced between the approximate limits of. six per cent and sixteen per cent. More manganese may be added but it will not as a rule bring about an improvement in properties sufficient to warrant the additional expense The lron-chromium-manganese alloys are discussed in more detail in my application benal N 0. 435,957, filed March 14, 1930. As s there stated the workability of the alloy increases as the carbon content is diminished, and where severe working operations are contemplated the carbon content should not be above-about three tenths per cent and is preferably below twelve hundredths per cent.

The iron-chromium-manganese may be additionally modified by the incor oration of other elements, and without sacri cing its resistance to corrosion by sulphur compounds.

Thus I may add copper in proportions from about one fourth of one per cent up to about three per cent. A substantial addition to co per tends to improve the deep drawing quali- PICS of the alloy as is more fully explained in my application Serial No. 444,876, filed Aprll 16, 1930. lfixcessive proportions of copper engender. a tendency towards -hot shortness. of copper, application, depends in some measure on the proportion of manganese present.

The maximum useful proportion A principal field of application for the pounds associated with the material being cracked and contained within the tubes; The alloys are in all respects admirably adapted to the fabrication of tubes for such operations, and they are equally suitable for making the tubular condensers in which the cracked products are usually liquefied.

This application is a division of a prior 100 as is explained in my said prior.

16%; copper about 0.25% to 2.5%; bon, the carbon content being not more than application, Serial Number 448,128, filed April 29, 1930.

claim:

1. An oil cracking tube composed of a stain-resisting iron-base alloy haying deepdrawingmproperties and containing mium a ut 16% .to 22%; manganese about than about 0.3%; tially iron.

2. An oil cracking with the balance substandrawing properties and contamingfihromium about 16% to 22%; manganese a ut 6% to ab0ut0.12%; with the balance substantially iron.

In testimon whereof I aflixm sigma.

F EDERIK M. B c 'r.

to 16%; copper about 0.25% to 2.5%; and carbon, the carbon content being not more tube composed of a stain-resisting iron-basealloy having deepand car-' 

